Door lock cylinder plate

ABSTRACT

A guard plate for a cylinder lock or the like includes a base and a mesa portion extending from the base and having an opening formed therein. When the plate is installed over the lock, that opening is in alignment with the axial end of the lock and the mesa portion prevents that axial end of the lock from being grasped and wrenched open, while permitting access to the lock for key operation through the opening. The guard plate further includes a second opening spaced relative to the first opening to permit the passage therethrough of a door handle. The openings are movable with respect to one another to permit the guard plate to be used on doors having different arrangements of the lock and door handle.

United States Patent n 1 Miller 154] DOOR LOCK CYLINDER PLATE [76] Inventor: Allan Miller, 5 Shaw Lane, Irvingt0n,N.Y.

[22] Filed: Nov. 1, 1971 [21] Appl. No.: 194,170

[52] U.S. Cl ..70/452, 70/461 [51] Int. Cl. ..E05b 9/08 [58] Field of Search ..70/452, 451, 461,

[56] References Cited U NITED STATES PATENTS 2,728,597 12/1955 Young.... .....292/357X 1 51 May 15,1973

121,758 7/1901 Germany ..70/452 Primary Examiner-Robert L. Wolfe Attorney-Sandae, Hopgood & Calimafde [57] ABSTRACT A guard plate for a cylinder lock or the like includes a base and a mesa portion extending from the base and having an opening formed therein. When the plate is installed over the lock, that opening is in alignment with the axial end of the lock and the mesa portion prevents that axial end of the lock from being grasped and wrenched open, while permitting access to the lock for key operation through the opening. The guard plate further includes a second opening spaced relative to the first opening to permit the passage therethrough of a door handle. The openings are movable with respect to one another to permit the guard plate to be used on doors having different arrangements of the lock and door handle.

4 Claims, 5 Drawing Figures DOOR' LOCK CYLINDER'PLA-TE The present invention relates generally to locks, and more particularly to a guard plate for preventing the unwanted tampering of a cylinder lock.

In a time in which the rate of occurrence of crimes against property and person are rising at an alarming rate, there is a growing concern to have the best available protection against intruders. For this reason, increased use is being made by home and apartment dwellers of locks and other protective devices that are placed at all possible entrances to their residences.

One of the most common type of lock employed for this purpose is the cylinder lock, in which the introduction of the proper key causes an alignment of pins within the lock to permit a cylinder or barrel to be rotated and the door containing the lock to either be locked or unlocked. To facilitate the opening and closing of the thus unlocked door, a door handle or knob adapted to be manually grasped is commonly provided on the door either directly above or below the lock.

In most installations of cylinder locks, the axial end of the lock, that is, the end of the lock that receives the key, extends at least slightly beyond the vertical plane of the door. That axially extending portion can be gripped by a visegrip, wrench, or the like, and then forcibly rotated to unlock the door without the need for a key. This lock tampering technique, which is known to burglars and other intruders, significantly decreases the reliability of protection offered by cylinder locks, and increases the possibility of forcible entry into the locked premises.

In an attempt to overcome this problem, a flat rectangular plate has been marketed which is adapted to be placed over the lock. The plate has a thickness equal to or greater than the axial extension of the lock from the door and thereby prevents the lock from being gripped. An opening is formed in the plate to permit a key to be inserted into the lock. That plate, however, provides only slightly improved protection against gripping, and, moreover, makes no provision for the passage of a door handle. As a result, the plate cannot be used on doors in which the door handle is closely spaced to the lock, as is most often the case. In addition, the known cylinder-lock guard plate detracts from the appearance of the door when employed, and accordingly has found only limited acceptance.

It is a general object of the invention to provide improved protection for a locked residence.

It is a further object of the invention to provide increased protection against the tampering of a cylinder lock or the like.

It is another object of the invention to provide a guard plate for a cylinder lock or the like which can be employed on a door of the type having a handle spaced from the lock, and which can be employed to advantage on doors having varying spacings between the handle and lock.

It is yet a further object of the invention to provide a guard plate of the type described by means of which the gripping of the end of a cylinder lock or the like bya tool is effectively prevented and which is economical,

attractive, and readily installed on the door containing the lock.

To this end, the lock guard plate of the invention includes a raised mesa-like portion formed on a base. That raised portion has a first opening formed therein that is adapted-to be placed over the exposed axial end of a lock. The raised portion, however, extends from the door to an extent greater than the axial extension of the look from the door such that the end of the lock cannot be grasped and forcibly. turned by a burglars tool. The provision of the opening in the raised portion permits the introduction of a key into the lock so that the use of the lock by the proper individuals is unhampered.

The guard plate of the invention further includes a second opening formed in the base and spaced from the first opening to allow the door handle to pass through the plate. To enable the guard plate to be employed on a variety of different doors having varying distances between the lock and handle, the second opening is movable with respect to the first opening.

As in the embodiment of the invention herein disclosed, the guard plate may further include a fixed elongated aperture formed in the base spaced from the first opening and a plate that is movably secured to the base and has a smaller aperture formed therein. The movable plate along with its smaller aperture is axially movable with respect to the fixed elongated aperture. The second or handle-receiving opening is defined by the alignment of the smaller aperture and the elongated aperture at the position of the former determined by the position of the movable plate to which the movable plate is set in accordance with the lock-to-handle spacmg.

In the embodiment of the invention herein specifically described, the movable plate is movably secured to the base by means of a resilient wire which includes an end portion that passes through the elongated aperture to engage the rear, door-engaging surface of the guard plate. That end portion is urged against the door surface when the guard plate is affixed to the door and creates a frictional force with the door surface, the force being effective to prevent further movement of the movable plate along the base.

To the accomplishment of the above and to such further objects as may hereinafter appear, the present inventionrelates to a door lock guard plate substantially as defined in the appended claims, and as described in the following specification taken together with the accompanying drawing in which:

FIG. 1 is a perspective, fragmentary view of a door employing the lock guard plate of the invention;

FIG. 2 is a cross-sectional view taken across the line 2-2 of FIG. I;

FIG. 3 is a rear'elevation of the lock guard plate of the invention;

FIG. 4 is an elevation view, on an enlarged scale as compared to FIG. I, of the lock guard section of a lock guard plate according to an alternate embodiment of the invention; and

FIG. 5 is a cross-sectional view taken across the line 55 of FIG. 4.

Referring now to the drawings, a cylinder 10 is fixed to a door 12 and has a bolt 14 mechanically coupled to its operating element which is moved transversely in response to the introduction and rotation of a suitable key into a slot formed in an axial end of lock 10 that is accessible at the door, to either lock or unlock the door according to the direction of rotation of the key and the lock barrel.

As is conventional, a handle or knob 16, here shown as being spaced below lock 10, is rotatably secured to door 12 to facilitate the opening of door 12 after it is unlocked by the operation of lock 10. Other door and lock arrangements may include a dual bolt assembly coupled respectively to the lock and door handle. The lock guard plate of the present invention has equal utility on doors of both types.

As seen best in FIG. 2, the axial end 19 of lock extends a slight distance beyond the vertical surface of the door. A would-be burglar is often able to grasp this axially extending end of the lock by means of a vise or other gripping tool, and by the use of this implement, to forcibly rotate the lock barrel and to thereby remove the lock from the door. Once the lock is thus removed from the door, the burglar is then able to open the door merely by manually operating the lock bolt.

The possibility that such forcible operation can be made on a lock of the type described is prevented by the guard plate of the invention. The guard plate, which is generally designated 20 in the drawing, is affixed to door 12 by suitable fastening means such as bolts 22 and reliably prevents the undesired grasping of end 19 of lock 10 while still permitting unhindered operation of the lock and door by a key.

As shown in the embodiment of the invention illustrated in FIGS. l-3, guard plate 20 includes a generally rectangular base 24. An upper raised or mesa portion 26 extends outwardly from base 24 and defines a hollow interior 28 (FIG. 3) between the plane of base 24 and an outer circular surface 30 of mesa portion 26. An offset opening 32 is formed in surface 30, opening 32 having a diameter that is sufficiently large to allow a key to be readily inserted therein but sufficiently small such that a vise grip, wrench, or similar tool cannot be passed therethrough for the purpose of grasping the axial end of the lock.

Thus, as seen best in FIG. 2, when guard plate 20 is affixed to the door such that opening 32 is in axial registration with the key-receiving axial end 19 of the lock, surface 30 extends from the door surface by an amount exceeding the distance that end 19 of the lock extends from the door surface. As a result, the end of the lock is effectively prevented from being grasped by a tool employed by a burglar while still permitting the ready access to the key slot through opening 32.

The peripheral surface of mesa portion 26 is preferably tapered outwardly so that mesa portion 26 is substantially frustoconical in form (FIGS. 1 and 2) to prevent a would-be burglar from obtaining a secure grip on that surface in an attempt to forcibly remove the mesa portion from the guard plate or to distort its shape in an attempt to gain access to the axial end of the lock.

The guard plate of the invention also includes provision for having a door handle such as handle 16 passing therethrough. To this end, an elongated ellipsoidal opening 34 is formed in base 24 and has a major axis extending coaxially with the vertical diameter of opening 30 from which opening 34 is vertically spaced (FIG. 3). A circular plate 36 has an opening 38 formed centrally therein that has a diameter substantially equal to the minor axis of opening 34. Plate 36 is secured to base 24 by means that are more completely described below, such that plate 36 can be moved vertically along the major axis of opening 34 so that opening 38 can be placed in registration with a selected portion of opening 34.

The thus aligned openings 34 and 38 define a selectively, vertically positionable composite opening through which the stem of handle 16 can pass. The position of that composite opening is determined by the level to which movable plate 36 and opening 38 are set. The ability of the composite opening to be positioned over a relatively wide range with respect to the fixed opening 30 permits the guard plate of the invention to be employed on a great variety of doors having different vertical spacing between the lock and door handle.

In the use of the lock guard plate of the invention, the handle or door knob is removed from the door, and the guard plate is affixed to the door at a level such that opening 32 overlies the exposed axial end of lock 10. Plate 36 is then moved vertically along base 24 until opening 38 comes into registration with fixed opening 34 at the level of the handle-receiving opening of the door, to allow the stern of the handle to pass through the guard plate. The handle is then replaced and secured onto its stem.

FIGS. 2 and 3 illustrate the manner in which plate 36 is movably secured to base 24 in a manner permitting the ready vertical movement of the plate along the base to its desired vertical position, as well as the manner by which it is securely held at that position. As shown, pins 40 and 42 extend axially from plate 36 and are radially spaced from opening 38. The apexes of a pair of V- shaped resilient wires 44 and 46 are respectively placed over pins 40 and 42. The legs 48 and 50 of pins 40 and 42 extend along the outer surface of base 24 and terminate in feet 52 and 54 which pass through opening 34 and are pressed against the rear surface of base 24. The resulting frictional force between wires 44 and 46 and base 24 permits plate 36 to be moved vertically along the base with respect to opening 34, but also securely retains plate 36 to base 24 when the former is at its desired position.

In addition, when guard plate 20 is affixed to the door surface, the legs 52 and 54 of the wires are pressed into the wood surface of the door and provide additional frictional force to retain plate 36 at its desired position.

FIGS. 4 and 5 illustrate an alternate embodiment of the lock guard plate of the invention which differs from the above-described embodiment of FIGS. l-3, in that the mesa portion 26a of the alternate embodiment is cylindrical in form rather than the tapered conical form of the earlier-described embodiment.

The lock guard plate of the invention thus provides significant added protection to a premises protected by a conventional lock, such as a cylinder lock, by pre venting a would-be intruder from grasping and turning the lock by the use of a wrench or vise tool. Moreover, the plate permits ready access to the look by the holder of a key, and allows the plate to be used on doors having different spacing between the lock and door handle.

The guard plate of the invention is economical to manufacture and can be sold at a low price, thus making it attractive to purchaers seeking the additional security afforded by the plate. The plate is moreover attractive and can be matched in appearance to the finish of either the door or the handle, to thereby enhance the appearance of the door.

As herein shown, the handle-receiving composite opening is movable with respect to the fixed, keyaccess opening. If desired, the key access opening may be made movable with respect to a fixed handlereceiving opening. In addition, other means for movably securing the movable plate to the base may be employed in place of the resilient wires as in the embodiment of the invention herein specifically disclosed.

Moreover, in an alternative construction of the guard plate of the invention, the movable plate 36 may be secured to the base plate at a selected position to achieve the desired spacing between the fixed and movable openings by means of screws rather than the wires as hereinabove specifically disclosed. To this end the customer after determining the location of the handlereceiving opening would drill or otherwise form two holes in the base plate to receive the fastening screws.

Thus, while the invention has been herein specifically disclosed with respect to several preferred embodiments, it will be apparent that modifications may be made therein all without departing from the spirit and scope of the invention.

I claim:

1. In an improved lock guard plate for mounting on a door having a door lock mounted in proximity with a door handle, the plate including an elongated aperture, a movable member generally covering the aperture and defining an opening, and adjustable mounting means for mounting the movable member over the elongated aperture, the improvement comprising: the adjustable mounting means comprising two resilient members connected to the movable member; said resilient members extending toward each other and projecting generally transversely, entirely through the elongated aperture to frictionally engage a rear face of the guard plate and the door when the guard plate is mounted thereon.

2. The improvement according to claim 1 wherein each resilient element comprises 'a V-shaped wire form attached to the movable member at the apex of said wire form.

3. The improvement according to claim 2 wherein terminal free ends of said elements are bent to define feet generally aligned with the longitudinal'extension of the elongated aperture.

4. The improvement according to claim 3 wherein said feet engage edges of the plate defining longitudinal ends of the elongated aperture when the plate is mounted on a door. 

1. In an improved lock guard plate for mounting on a door having a door lock mounted in proximity with a door handle, the plate including an elongated aperture, a movable member generally covering the aperture and defining an opening, and adjustable mounting means for mounting the movable member over the elongated aperture, the improvement comprising: the adjustable mounting means comprising two resilient members connected to the movable member; said resilient members extending toward each other and projecting generally transversely, entirely through the elongated aperture to frictionally engage a rear face of the guard plate and the door when the guard plate is mounted thereon.
 2. The improvement according to claim 1 wherein each resilient element comprises a V-shaped wire form attached to the movable member at the apex of said wire form.
 3. The improvement according to claim 2 wherein terminal free ends of said elements are bent to define feet generally aligned with the longitudinal extension of the elongated aperture.
 4. The improvement according to claim 3 wherein said feet engage edges of the plate defining longitudinal ends of the elongated aperture when the plate is mounted on a door. 